Patent GB-489881-A (GB)
Title: Improvements in mechanical pencils
IPC: B43K21/22
Filed: 1937-04-19
Abstract: 489,881. Pencil holders. WAHL CO. April 19, 1937, No. 11168. Convention date, June 18, 1936. [Class 146 (iii)] In a step-by-step propelling pencil of the type in which a lead clutch is reciprocable longitudinally with a lead guide tube within the pencil barrel, the clutch having gripping jaws which, towards the end of the rearward movement of the clutch are wedged inward by a gripping member which is reciprocable with the clutch but through a smaller distance, the member being held in frictional engagement with the clutch for forward movement with it, the clutch carries latching means which becomes effective substantially at the end of the forward movement of the clutch to latch the constricting member out of jaw-wedging relationship therewith, and then holds the restricting member for rearward movement with the clutch and retains it out of jaw-wedging relation until after it has reached the end of its rearward movement. The barrel 10, Fig. 1, of metal, celluloid, or other material, has a shoulder against which seats a guide bushing 12 which may be screwed or moulded into the barrel, and on to which screws a tip 20, provided with a surface 21, Fig. 3, co-operating with a surface on the bushing to secure exact alignment. Slidably mounted in the barrel is a member comprising a magazine 31 and guide tube 32; it is guided at one end by the bushing 12, and at the other by a screwed on ferrule 49. The shoulder 50 on the ferrule 49 engages a stop 51 on the tube 31, 32 and retains the latter in the barrel. A split clamp 38 fits into a socket 37 at the forward end of the tube 32 and is retained by a swaging 40. The arms of the clamp, toothed at 41 and with a conical outer surface at 42, normally spring outwards but are closed to grip the lead by a member 52, which is guided in a bore 18 in the bushing 12, and can slide between shoulders 54, 25. A reversible eraser holder is held by a bayonet catch in the end of the magazine 31, and may be removed for the introduction of leads through a gauge 59 shaped so as to reject all leads of unsuitable size and shape. The leads move down the conical base 35 of the magazine and enter the tube 32 one by one and are arrested by the teeth 41. If the member 31, 32 is pressed forward against the action of a spring 46, the member 52 is presently arrested by the shoulder 25, and the jaws 42 then open to allow the leads to fall into contact with a springy clamp 30 in the tip. When the member 31, 32 returns, the member 52 is first carried back without the jaws closing by the latching action of steeply conical shoulders 44 on the jaws 42, but is presently arrested by the shoulder 54 and the jaws then close on the lead and are held closed by action of the spring 46. A second and subsequent reciprocation of the member 31, 32 feeds the leads through the clamp 30 until the magazine is empty. The jaws can then close to their full extent so that the last return of the member 32 is to the limit of the shoulder 50, thus signalling that the pencil is empty. In a modification, Fig. 7, the ferrule 49 is omitted and the rearward movement of the tube 32 is halted by a collar 61 engaging a shoulder 13 in the sleeve 12, which in this case is in two parts, a part 12b with a counterbore 12c, fitting into a bore in the part 12a and against the shoulder 13. In both forms the pencil can be disassembled by unscrewing the ferrule 49.